Set during the height of World War II, Horizon centers on a secretary at the FBI (Big Thunder's Ruth Bradley) who discovers that her husband might have been killed in a battle with a spaceship in the South Pacific. Obsessed with learning the truth, she becomes the only person standing between Earth and an alien invasion.

Elwes will portray Max Hartman, a mysterious man who leads a double life in wartime D.C. The pain of his tragic past prompts him to question whether he should follow orders or do what he knows is right.

The actor, who returns to USA following a role on Psych, joins a cast that includes Bradley, Meg Steedle (Boardwalk Empire), Mark Famiglietti (Live at the Fox Den) and Taylor Handley (Vegas).

The Walking Dead's Gale Anne Hurd will executive produce the drama alongside Burn Notice's Bridget Tyler, who will pen the script for Horizon. The project is part of The Walking Dead executive producer's recent pod deal for her Valhalla Entertainment banner with Universal Cable Productions. Yves Simoneau (V) will direct.

Elwes, whose credits also include Days of Thunder, Liar, Liar and Behaving Badly, is repped by APA and Kritzer Levine.